1. Field of the Invention
The present invention relates to an apparatus for inspecting a liquid crystal panel, and more particularly to the apparatus for inspecting the liquid crystal panel capable of handling a fine pitch and reducing inspection time.
2. Discussion of the Related Art
In general, a liquid crystal display produces a picture by means of adjusting a light transmittance of a liquid crystal using an electric field. For this purpose, the liquid crystal display comprises a liquid crystal panel where liquid crystal cells are arranged in a matrix pattern and a driving circuit for driving this liquid crystal panel.
In a liquid crystal panel, gate lines and data lines are arranged perpendicularly and liquid crystal cells are located in the region where gate lines and data lines intersect. The liquid crystal panel is provided with pixel electrodes and common electrodes for applying an electric field to the respective liquid crystal cells in this liquid crystal panel. Each of the pixel electrodes are connected to a data line through a source and a drain electrode of a thin film transistor, which is used as a switching apparatus. The gate terminal of the thin film transistor is connected to one of the gate lines on which a video signal is applied to pixel electrodes.
The driving circuit comprises a gate driver to drive the gate lines, a data driver to drive the data lines, a timing controller to control the gate driver and the data driver and the power supply to supply various driving voltages used in the liquid crystal display. The timing controller controls a driving time of the gate driver and the data driver and in addition supplies pixel data to the data driver.
The power supply generates the driving voltages such as a common voltage (Vcom), a gate high voltage (Vgh), a gate low voltage (Vgl) as necessary to drive the liquid crystal display. The gate driver sequentially supplies a scanning signal to the gate lines to sequentially drive liquid crystal cells on the liquid crystal panel one line at a time. The data driver generates a video signal by using a pixel data and supplies the generated video signal to each data lines whenever a scanning signal is supplied to any one of the gate lines. Hereby, the liquid crystal display represents the picture by means of adjusting for each liquid crystal cell the light transmittance using the electric field applied between the pixel electrode and the common electrode in accordance with the video signal.
The data driver and the gate driver that are directly connected to the liquid crystal panel are integrated into a plurality of integrated circuits (IC). Each of the integrated data driver ICs and the gate driver ICs are mounted on a TCP (Tape Carrier Package) and then are connected to the liquid crystal panel using a TAB (Tape Automated Bonding) system or are mounted on the liquid crystal panel using a COG (Chip On Glass) system.
Herein, the drive ICs connected to the liquid crystal panel by the TAB system through the TCP receive control signals and DC voltages from a PCB (Printed Circuit Board, that is, the timing controller and the power supply) connected to the TCP.
The drive ICs mounted in the liquid crystal panel by the COG system are connected to each other by a LOG (Line On Glass) system where the signal lines are mounted on the liquid crystal panel, that is, a lower glass, and in addition receive the control signals and the driving voltages from the timing controller and the power supply.
Before the TCP is connected to the liquid crystal panel, bad pixels of the liquid crystal panel are inspected by using an inspecting apparatus (such as an auto probe). More specifically, after the liquid crystal panel is finished, each bad pixel of the liquid crystal panel is checked and a reliable liquid crystal panel is provided by means of repairing the checked bad pixels. Afterwards, the liquid crystal panel is connected to the TCP.
As shown in FIG. 1, before being connected to the TCP, the liquid crystal display comprises a liquid crystal panel 2 and pads 8 and 10 formed in the upper and the left ends of the liquid crystal panel 2. The liquid crystal panel 2 includes liquid crystal between an upper substrate and a lower substrate. A thin film transistor array is formed together with various signal lines on the lower substrate, and a color filer array is formed on the upper substrate. The liquid crystal panel 2 includes a liquid crystal cell provided at intersections of gate lines 6 and data lines 4 to define a picture display region 12 for displaying the picture.
In an external region of the lower substrate located in the external part of the picture display region 12, data pads 8 extending from the data line 4 and gate pads 10 extending from the gate line 6 are located. After the liquid crystal panel 2 is completed, the bad pixels of the liquid crystal panel 2 are checked by using an apparatus for inspecting the liquid crystal panel 14.
Referring to FIG. 2, the conventional apparatus for inspecting the liquid crystal panel comprises a PCB 16, a TCP 18 and a connector 20.
The timing controller and the power supply are mounted in the PCB 16. The timing controller and the power supply generate control signals and DC voltage. The PCB 16 is fixed by a supporting member (not shown).
One side of the TCP 18 is electrically connected to the PCB 16. A drive IC 22 is mounted on each TCP 18. The drive IC 22 generates a driving signal supplied to the data pad 8 and the gate pad 10 using the control signals and the DC voltage supplied from the PCB 16. The driving signal generated by the drive IC 22 of the TCP 18 is supplied to the data pad 8 or the gate pad 10 and in turn to the gate lines 6 and the data lines 4.
The connector 20 supplies the driving signals supplied from the TCP 18 to the pads 8 and 10. For this purpose, the one side of the connector 20 is connected so that it may be fixed to the other side of the TCP 18. Namely, the connector 20 is electrically connected to the pads of the TCP 18 (not shown).
On the other hand, the connector 20 comprises a plurality of pins 24 as shown in FIGS. 3 and 4a. The pins 24 are fixed to the connector 20 to supply the driving signal from the TCP 18 to the pads 8 and 10. More specifically, the pins 24 are set up between pads (not shown) of the TCP 18 and the pads 8 and 10 of the liquid crystal panel 2 and electrically connect the pad of the TCP 18 and the pads 8 and 10 of the liquid crystal panel 2.
In accordance with the present invention, the pins 24 are arranged in four columns in order to prevent a short circuit with adjacent pins 24. More specifically, as shown in FIG. 4a, the pins are alternately arranged in order to locate in each other different column with adjacent pins 24. And, as shown in FIG. 4b, the pins 24 are adhered to the pads 8 and 10 with a predetermined elastic force. After the pins 24 are connected to the pads 8 and 10, the apparatus 14 for inspecting the liquid crystal, that is, the TCP 18, inspects bad pixels of the liquid crystal panel 2 by providing a designated pattern signal and a signal turning the device on and off.
As described above, the conventional apparatus for inspecting a liquid crystal panel 14 is electrically connected to the pads 8 and 10 of the liquid crystal panel 2 by using a plurality of pins 24. Here, since each of pins 24 has a protrusion at its end for contact, a bending of the pins 24 can occur during fabrication. For example, since the pins 24 can be bent if they catch on the clothes or gloves of an operator, it is difficult to inspect exactly. In addition, since the pins 24 are arranged in 4 rows, it is difficult to find which particular pin is bent. Further, a short circuit may arise if a material falls between the pins 24. And in order to combine a plurality of pins 24 with the desired pads 8,10, much fabrication time is needed. In particular, the finer the pitch of the pads of the liquid crystal panel 2 the more this phenomena arises.